Use of transition metal carbonyls in the manufacture of cyclopentadienyl manganese tricarbonyl



United States Patent USE OF TRANSITION METAL CARBONYLS IN THE MANUFACTURE OF CYCLOPENTADIENYL MANGANESE TRICARBONYL Leslie L. Sims, Baton Rouge, La., assignor to Ethyl Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed Apr. 25, 1958, Ser. No. 730,786

3 Claims. (Cl. 260-429) This invention relates to the manufacture of cyclopentadienyl manganese compounds and more particularly to the manufacture of cyclopentadienyl manganese tricarbonyl compounds.

Cyclopentadienyl manganese tricarbonyl compounds have been found to be exceptionally effective antiknocks for use in fuels for spark plug ignition internal combustion engines. These compounds not only have exceptional effectiveness as antiknocks but also many of these compounds have auxiliary properties which make them practical and desirable for commercial use. These auxiliary properties include high solubility in fuels, such as gasoline, and thermostability either alone or in gasolines which makes these compounds entirely satisfactory for use under the widely varying conditions to which gasoline and other fuels are normally subjected. Possibly of even greater importance these compounds do not tend to form any appreciable deposits on the engine pistons, valves and spark plug surfaces and likewise are not abrasive to the engine parts as are characteristic of iron compounds.

It is accordingly an object of this invention to provide an improved process for the manufacture of cyclopentadienyl manganese tricarbonyl compounds. Another objects is to provide a process of the above type having an exceedingly fast reaction rate and capable of operation at relatively low temperatures and carbon monoxide pressure. Still another object is to provide a process which gives improved yield of the desired product. Another object is to provide a process which has a high throughput per unit quantity of reactor space and which is adapted to employ simple and economic process equipment. Other objects and advantages of the invention will be more apparent from the following description and appended claims.

It has now been found that cyclopentadienyl manganese tricarbonyl compounds can be produced in excellent yields by reacting cyclopentadienyl manganese compounds with carbon monoxide in the presence of metal carbonyls, particularly transition metal carbonyls, preferably employed in catalytic quantities. Most preferred are carbonyls of metals having an atomic number ranging from 24 to 28 inclusive, specifically chromium manganese, iron, cobalt and nickel. By a transition metal is meant metals of group V-B, VI-B, VIIB, and VIH of the periodic table (Handbook of Chemistry and Physics, 36th ed., pp. 392 and 393).

More specifically, the process of this invention comprises reacting a cyclopentadienyl manganese compound, e.g. a bis(cyclopentadienyl) manganese compound or a cyclopentadienyl manganese salt with carbon monoxide gas, preferably in a liquid media which is a solvent for the cyclopentadienyl manganese compound, in the presence of from about 0.01 to 30 mole percent of a transition metal carbonyl at a temperature of from about 0 to 250 C., preferably from about 75 to 200 C. The cyclopentadienyl radical is a cyclomatic radical having a 5-carbon ring corresponding to the ring in cyclopentadiene itself. Generally, carbon monoxide pressure ranging from subatmospheric to superatmospheric, i.e. 2,000 atmospheres, can be employed but usually pressures of from about 25 p.s.i.g. to 5,000 p.s.i.g. are preferred. The presence of the transition metal carbonyl permits Patented June 6, 1961 materially lower carbon monoxide pressure for a given temperature and reaction or, conversely, the temperature can be lowered and/or increased rates can be obtained with the same or only moderately lower carbon monoxide pressures.

The catalytic activity of metal carbonyls in the process of this invention is completely unexpected and unpredictable. At the same time, the effectiveness of these catalysts is very pronounced and the resulting advantages are extremely important from a commerical standpoint. The reason for the catalytic activity of these metal carbonyls is not understood. However, it is apparent that their activity is not due to carbonylation of the manganese by the carbonyl groups of the metal carbonyl. In fact, in the absence of gaseous carbon monoxide the rate of reaction is considerably slower than with gaseous carbon monoxide alone and the overall product yield is ma terially less than in the process of this invention. It also might be theorized that the transition metal carbonyl is converted to the corresponding metal cyclopentadienyl compound. However, this is unlikely since, in the case of iron carbonyls, ferrocene would be produced which is a highly stable and a relatively inert material. Moreover, neither ferrocene or the mixed compound dicyclopentadienyl diiron tetracarbonyl are eifeetive catalysts.

The actual rate of carbonylation of cyclopentadienyl manganese compounds in the presence of transition metal carbonyls is increased percent or more and, at the same time, the reaction can be conducted at materially lower temperatures. In addition, the transition metal carbonyls even improve the yield of the desired cyclopentadienyl manganse tricarbonyl product. For example, in carbonylating bis(cyclopentadienyl) manganese in controlled experiments using about 700 pounds of carbon monoxide pressure, the manganese compound was completely carbonylated in about 1 /2 hours, using 5 mole percent of iron pentacarbonyl (Fe(CO) whereas from 2 /2 to 4 /2 hours were required in the absence of iron pentacarbonyl. Moreover, the reaction with iron carbonyl had an excellent rate of reaction at temperatures above about 100 C. whereas no appreciable carbonylation took place at temperatures below about to C. without the iron pentacarbonyl. Moreover, the yield of cyclopentadienyl manganese tricarbonyl with the iron pentacarbonyl was 77.5 percent, compared to only 74.5 percent when no iron car-bonyl was employed.

In carrying out the process of this invention, it is generally desirable to employ a solvent, preferably an ether, which has a boiling point above the operating temperature of the reaction, or at least, which exerts a vapor pressure which is less than about 50 percent of the carbon monoxide pressure.

The liquid media suitable for the process of this invention can be any solvent or complexing agent for the manganese compound. In general, suitable solvents are ethers, amines, amides, nitriles, and the like. The ethers can be either aliphatic or aromatic, such as dimethyl ether, diethyl ether, methylethyl ether, anisole, diphenyl ether and, in general, any ether which is liquid at the reaction temperature and pressure employed. Preferred ethers are the cyclic ethers and the ethylene glycol type ethers. Typical examples are dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, and corresponding higher alkyl ethers, such as diethyl, methyl ethyl, dibutyl, and the like. Typical examples of diethylene glycol dialkyl ethers are the dimethyl, diethyl, methyl ethyl, dibutyl and the triethylene glycol ethers including the dimethyl, diethyl, diisopropyl, and the like. In general the preferred ethylene glycol dialkyl ethers have alkyl groups containing from 1 to 6 carbon atoms.

Suitable amine solvents for use in this invention are manganese tricarbonyl,

propyl amine, diethyl amine, di-n-propyl amine, dibutyl amine, triethyl amine, triisopropyl amine, and other amines having from 2 to 10 carbon atoms per alkyl group. Aromatic amines are also suitable, such as aniline, methyl aniline, dimethyl aniline, trimethyl aniline, and similar compounds. A particularly suitable amine solvent is dicyclohexylamine.

Typical examples of suitable amides are formamide, and the monoand dialkyl formamides, such as N,N-dimethyl formamide, containing alkyl groups having from 1 to 6 carbon atoms. Other suitable amides are cyclic amides, such as N-methyl pyrrolidone and other alkyl pyrrolidones and amides of inorganic acids, such as hexamethyl phosphoramide.

Suitable nitriles which can be employed as solvents in this invention are acetonitrile, propionitrile, butyronitrile and the like.

The liquid media can be employed in a wide range of concentration from about 0.5 mole, based upon the manganese compound, to about 30 moles. Higher dilution of the reaction mixture can be employed except that no appreciable improvement in the reaction is obtained and considerably greater difiiculty is encountered in the recovery of the desired product.

The compounds which can be made by the process of this invention are any cyclopentadienyl manganese tricarbonyl compounds, including substituted cyclopentadienyl compounds, such as the indenyl and fluorenyl derivatives. Typical examples of such compounds are cyclopentadienyl manganese tricarbonyl, methylcyclopentadienyl manganese tricarbonyl, n-butylcyclopentadienyl manganese tricarbonyl, isobutylcyclopentadienyl n-decylcyclopentadienyl manganese tricarbonyl, phenylcyclopentadienyl manganese tricarbonyl, methylphenylcyclopentadienyl manganese tricarbonyl, indenyl manganese tricarbonyl and fluorenyl manganese tricarbonyl. For fuel use, the preferred compounds are those containing up to about 12 carbon atoms in the cyclopentadienyl group.

The following are typical examples of the present invention and are given for the purpose of illustration and not a limitation. In these examples, all quantitative units are in parts by Weight.

Example I Bis(cyclopentadienyl) manganese dissolved in a molar equivalent of diethylene glycol diethyl ether was placed in a pressure reaction vessel provided with a stirrer. To this solution was added mole percent (based on his- (cyclopentadienyl) manganese) of iron pentacarbonyl. Carbon monoxide was fed to the reactor giving a pressure of 610 p.s.i.g. The reaction mixture was then heated from room temperature up to 165 C. At about 100 C. the carbon monoxide pressure in the reactor began to decrease, indicating an initiation of the carbonylation reaction. Upon attainment of a temperature of 165 C., the carbon monoxide pressure had already fallen to 525 p.s.i.g., a drop of almost 400 p.s.i.g. from the calculated maximum reaction temperature pressure of 915 p.s.i.g. The reactor was then repressurized to 750 p.s.i.g. (at reaction temperature) and the reaction continued for a period until the pressure had again decreased to 650 p.s.i.g. The reactor was then repressurized to 750 p.s.i.g. several times in like manner. The reaction was complete after about 1 /2 hours, indicated by an absence of further pressure drop. The crude reaction mixture was thereafter fractionated at reduced pressure to remove the diethylene glycol dimethyl ether from the cyclopentadienyl manganese tricarbonyl product. The yield of cyclopentadienyl manganese tricarbonyl was 77.5 percent, based upon the bis(cyclopentadienyl) manganese.

The above product, after repurification by distillation, is used as an antiknock in accordance with the procedures given in US. Patent 2,818,417.

Theabove reaction' was repeated'except that no iron pentacarbonyl was employed during the carbonylation reaction. In contrast to the process using iron pentacarbonyl, no appreciable reaction took place until the reaction mixture had reached the reaction temperature of 165 C. and the carbon monoxide absorption was materially lower than when using the iron carbonyl, i.e. the yield was less than 75 percent.

The bis(cyclopentadienyl) manganese was prepared by reacting sodium metal with cyclopentadiene monomer (15 percent excess) in diethylene glycol dimethyl ether solvent at C. The reaction mixture was stirred during reaction until there was no evidence of further hydrogen evolution. This reaction mixture was then reacted with anhydrous manganous chloride (1.1 mole equivalents of manganous chloride) at reflux temperature (160-165" C.) The reaction mixture was again stirred throughout this reaction and the reaction product was filtered to remove the inorganic salts. The bis(cyclopentadienyl) manganese product in diethylene glycol dimethyl ether was then carbonylated in accordance with the above procedure.

Example II Example I was repeated except that bis(methylcyclopentadienyl) manganese was carbonylated using only 3 mole percent of iron pentacarbonyl. In this case the product was methylcyclopentadienyl manganese tricarbonyl. The maximum reaction pressure of carbon monoxide was 350 p.s.i.g. and the minimum reaction pressure was 300 p.s.i.g., 66 percent completed in 30 minutes. Virtually the same reaction rate increase was obtained in this run as in Example I and again a material increase in yield of desired product is obtained, that is, 83 percent yield using iron pentacarbonyl as compared with only about 72 percent yield in the absence of iron pentacarbonyl.

In this run the bis(methylcyclopentadienyl) manganese was produced by reacting sodium in diethylene glycol dimethyl ether with methylcyclopentadiene dimer at a temperature of about 190 C. This reaction product containing methylcyclopentadienyl sodium was thereafter reacted with the manganous chloride in accordance with the procedure given above for the manufacture of bis- (cyclopentadienyl) manganese.

Example III Example I is repeated except that a total of only 0.5 mole percent of iron pentacarbonyl is added to the reactor and this added in three equal portions beginning with an initial charge and two additional charges at 30-minute intervals. The cyclopentadienyl manganese tricarbonyl produced is recovered in excellent yield.

Example IV Example I is repeated except that bis(n-butylcyclopentadienyl) manganese is reacted in the presence of 3 moles of tetrahydrofuran instead of the glycol ether solvent and the reaction is conducted at 50 C. using 1000 p.s.i.g. carbon monoxide pressure. Cobalt carbonyl is employed instead of the iron carbonyl.

The n-butylcyclopentadienyl manganese tricarbonyl is recovered by distillation.

Example V Methylcyclopentadienyl manganese chloride is reacted with carbon monoxide (350 p.s.i.g.) at C. in diethylene glycol diethyl ether in the presence of nickel carbonyl. Similar results are obtained except that methylcyclopentadienyl manganese tricarbonyl is formed.

Exampvle VI Example I is repeated except that manganese pentacarbonyl dimer is employed in place of the iron carbonyl and the reaction is conducted in cyclopentadiene dimer at a temperature of C., using 500 p.s.i.g. of carbon monoxide. Similar results are obtained.

Example VII Example III was repeated except that bis(n-decylcyclopentadienyl) manganese is reacted with 800 p.s.i.g. of carbon monoxide at 80 C. in moles of toluene. A chromium carbonyl is employed using a catalyst in place of the iron carbonyl. The n-decylcyclopentadienyl manganese tricarbonyl is recovered in good yield.

Example VIII Bis(fiuorenyl) manganese is reacted with carbon monoxide (300 p.s.i.g.) using niobium carbonyl as a catalyst. This reaction is conducted in dicyclohexylamine solvent (0.1 mole) at 190 C. The fluorenyl manganese tricarbonyl is recovered by distillation at reduced pressure.

Example X Bis(2,4-methylphenylcyclopentadienyl) manganese is reacted with carbon monoxide (2000 p.s.i.g.) to form 2,4- methylphenylcyclopentadienyl manganese tricarbonyl. This reaction is carried out using 2 mole percent (based upon the manganese compound) of molybdenum carbonyl as a catalyst. The reaction is conducted in diethylene glycol dibutyl ether solvent at a temperature of 170 C.

Example XI Bis(cyclopentadienyl) manganese is reacted with carbon monoxide in the initial presence of nickel metal which forms the nickel carbonyl under reaction conditions. The reaction is conducted in diethylene glycol diethyl ether solvent at 150 C.

I claim:

1. A process for the manufacture of a cyclopentadienyl hydrocarbon manganese tricarbonyl comprising reacting a bis(cyclopentadienyl hydrocarbon) manganese with carbon monoxide while in contact with from about 0.01 to about mole percent of an inorganic transition metal carbonyl, said transition metal being selected from the group consisting of groups V-B, VI-B, VII-B and VIII of the periodic table, said carbon monoxide being maintained at a pressure of from about 25 p.s.i.g. to about 2,000 atmospheres.

2. The process of claim 1 wherein the process is conducted in a solvent at a temperature of from 0 to 150 C.

3. The process of claim 1 wherein the transition metal carbonyl is an iron carbonyl.

References Cited in the file of this patent UNITED STATES PATENTS 2,557,744 Hurd June 19, 1951 2,748,167 Hagemeyer et al May 29, 1956 2,810,736 Catlin et al. Oct. 22, 1957 2,818,417 Brown et al. Dec. 31, 1957 2,870,180 Kozikowski et al. Ian. 20, 1959 2,898,354 Shapiro et al. Aug. 4, 1959 2,916,506 Axtell et a1. Dec. 8, 1959 OTHER REFERENCES Deming: General Chemistry, 5th edition, New York,

John Wiley & Sons, Inc., copyright 1944, last page relied 

1. A PROCESS FOR THE MANUFACTURE OF A CYCLOPENTADIENYL HYDROCARBON MANGANESE TRICARBONYL COMPRISING REACTING A BIS(CYCLOPENTADIENYL HYDROCARBON) MANGANESE WITH CARBON MONOXIDE WHILE IN CONTACT WITH FROM ABOUT 0.01 TO ABOUT 30 MOLE PERCENT OF AN INORGANIC TRANSITION METAL CARBONYL, SAID TRANSITION METAL BEING SELECTED FROM THE GROUP CONSISTING OF GROUPS V-B, VI-B, VII-B AND VIII OF THE PERIODIC TABLE, SAID CARBON MONOXIDE BEING MAINTAINED AT A PRESSURE OF FROM ABOUT 25 P.S.I.G TO ABOUT 2,000 ATMOSPHERES. 